The valve operation of intake valves and exhaust valves of an internal combustion engine is controlled by a camshaft. A rotation of the camshaft is fixedly coupled to a rotation of the crankshaft so that a control of the intake valves and the exhaust valves takes place synchronously with a rotation of the crankshaft and, thus, synchronously with power strokes of the internal combustion engine.
Camshaft adjusters are used to vary the valve operation of an intake valve and/or an exhaust valve coupled to a rotation of a camshaft by adapting at least one valve actuating variable to influence the fresh air quantity flowing into a combustion chamber of a cylinder during an intake stroke of the internal combustion engine. This fresh air quantity determines the charge of the internal combustion engine, which in air-guided internal combustion engines largely defines the engine torque provided by the internal combustion engine.
The adjustment of the valve actuating variables may have tolerances of up to 6° crankshaft angle, in particular when they concern opening and closing times of the intake and/or exhaust valves. This may lead in specific operating states, for example in operating modes having a great amount of residual exhaust gas, to an increased error, which may result in an increase in emissions.